Generators, in particular those of large power generating plants, for example with an output in excess of 50 MW, are cooled during operation to protect them from damage caused by overheating. Suitable preferably as the coolant for this purpose is hydrogen, which in comparison with air has a heat dissipating capacity 18 times higher. To increase the effect of the cooling still further, the hydrogen is brought to superatmospheric pressure in the generator and, depending on the type of generator to be cooled, is used at a pressure of, for example, 2.0 bar to 5.25 bar.
Constant leakages have the effect that the generator is always losing hydrogen. To be able to ensure satisfactory operation of the generator, this amount of leakage must be compensated according to requirements, for which reason corresponding amounts of hydrogen have to be fed to the generator from time to time. In this connection, it is known from the prior art to provide hydrogen in gas cylinders or storage tanks and feed it to the generator according to requirements via corresponding pipelines. If, owing to the site, it is not possible for gas to be delivered in cylinders or by road tankers, it is also known from the prior art to generate hydrogen on site by use of potassium hydroxide electrolyzers, store it in appropriate tanks and feed it to the generator via a pipeline system.
A disadvantage of the way described above of storing, distributing and feeding hydrogen to the generator is the fact that, if there is a loss of integrity or leakages, the formation of ignitable gas mixtures can occur, with the result that a fire or even an explosion cannot be ruled out. Furthermore, in particular in the case of improper or unintentionally negligent handling of the hydrogen storage tanks, there is a high risk of an accident, which is particularly pronounced when the storage tanks are changed.
It has been attempted in the past to minimize the disadvantages and risks associated with the formation of ignitable gas mixtures by the evaporation brought about by natural ventilation, i.e. by allowing air to pass through. However, a residual risk remains in any case. Added to this is the fact that the hazard entailed in changing spent hydrogen storage tanks is countered only by corresponding work regulations, which of course is highly unsatisfactory, since such measures do not reduce the hazard itself but merely prevent improper handling. However, measures of this kind which prescribe handling procedures are often elaborate and time-consuming to implement, with the not infrequent result in practice that they are deliberately avoided by the operating personnel to make handling easier and quicker. They are therefore not really suitable for reducing the hazard on a long-term basis.